1. Field of the Invention
The present invention relates to a method of separating isotopes from gaseous mixtures of substances by means of excitation specific to the isotopes by electromagnetic radiation.
2. Description of the Prior Art
Laser radiation permits one to generate frequencies from the infrared to the ultraviolet region and to achieve high intensity in a very narrow frequency band. Such radiation is therefore suited for selectively exciting in a mixture of substances, those substances, the absorption spectrum of which exhibits absorption lines of that wavelength. Years ago, these properties of laser radiation led to using lasers for the purpose of isotope separation. In this connection, reference is made to the German Published Non-Prosecuted Application No. 1 959 767, in which excitation, specific to the isotope of the one isotope compound, is proposed, to thereby enable the excited isotope compound to react chemically with a reaction partner. Fractional distillation has been proposed for separating the reaction product, which preferably contains only the one isotope compound. The objective of this German Published Application as well as of many other publications was the separation of the isotopes of uranium in view of the increasing demand for enriched nuclear fuel and the extremely high technical as well as financial costs of enrichment plants, especially those operating according to the diffusion principle. All proposals were based on UF.sub.6 as this was practically the only gaseous uranium compound. It turned out, however, that the absorption lines in this compound are so close together at room temperature that the bands practically form a continuum. In addition, the bands of the isotope compounds 235 UF.sub.6 and 238 UF.sub. 6 overlap so much that selective excitation of the one isotope compound is possible only to a very limited extent. In the German Published Non-Prosecuted Application No. 2 447 762, the proposal was therefore made to adiabatically decompress the gaseous UF.sub.6 and to subsequently excite the one isotope compound and thereby enable it to enter into a chemical reaction with a reaction partner. The cooling down in the adiabatic expansion causes, so to speak, a freezing of the vibration states of the molecules and a reduction of the rotations, so that thereby a very substantial narrowing of the bands occurs, particularly of their Q-branch. This brings about a sufficient distance from the Q-branch of the other isotope compound and selective excitation becomes possible. Here, too, the chemical reaction product which contains the excited uranium isotope, must be separated and recovered by physical or chemical means.